Oil-well heater



Feb. 10, 1925.

c. L. REDFIELD OIL WELL HEATER Filed sept. 11. 1922 i Patented Feb. 10, 1925.

' UNITED STATES CASPER L. REDFIEL'D, 0F CHICAGO, ILLINOIS.

OIL-WELL HEATER.

Application led September 11, 1922. Serial No. 587,616.

To all whom t may concern:

Be it known that I, CASPER L. Rrnrmrn. a citizen of the United States of America, and a resident of Chicago, count-y of Coolr,

I and State of Illinois,'have invented certain new and useful Improvements in Oil-VVe-ll Heaters, of which the following is a speciiication.

My invention relates to electric heaters for l oil wells, and has for its object improvelments in such devices.

A typical oil well is about six inches in diameter and some two thousand feet, more or less, in depth. The oil bearing sand or 1I rock consists of a stratum twenty or thirty feet, more or less, in thickness.

Crude oil usually contains parafiin, and this parat'n hasa tendency to solidify in the pores of the sand around the well. This process'gradually seals the walls of the well and stops the flow of oil therefrom. The remedy is to melt the paraiiin by the application of heat, and pump it out.

The best means of accomplishing this is to use an electric heater which is less than six inches in diameter and is in the neighborhood of twenty feet long. This heater should be submerged in the oil of the well so that the circulation of the oil in contact with the heater will convey the heat to the walls of the well and heat those walls back for several yfeet around the bore ofthe well. Sometimes, during the heating operation, the walls of the well will cave in and bury the lower end of the heater in several feet of sand. In such circumstances the circulation around the buried lower end is stopped, and, unless there is provision to prevent injury, the lower end of the heater becomes overheated and burned out. And sometimes, during the heating operation, the oil in the well will subside and leave several feet of the upper end oi the heater in a dry hole. Under such. circumstances the upper end will become overheated and consequently damaged.

These difiiculties may be overcome by providing a special circulating medium within the heater, which medium will serve lto convey extra heat from the buried lower end, or from an upper end to which the oil in the well does not reach, to those parts of the heater which are still properly submerged in the oil of the well. The object of the present invention is to provide a more efficient circulation of this interior medium than has heretofore been possible.

In the accompanying drawin Fig. 1 is a sectional elevation of the upper part of the device;

Fig. 2 is a sectional elevation of the lower end; and

Fig. 3 is a section on line 3 3 of Fig. 1.

The casing 10 is between four and five inches in diameter for a six-inch well, and G5 is approximately twenty feet long, but may be much shorter for cases in which the oil bearing stratum is comparatively thin. The ends are closed by heads 11 and 12. The head l1 is provided with a stuiiing box for 70 the electric cable 14, and with a bail 15 by which the device may -be suspended Within the well by a wire rope reaching to the vsurface of the earth.

Secured within the casing l0 between the 75 heads 11 and 12 are other heads 16 and 17 which are alike in construction but which face in opposite directions. These heads have a central opening 1S and some peripheral recesses 19 which extend from face S0 to face. The object of this opening and these recesses is to place the two sides of the heads 16 and 17 in communication with each other as will be described.

At the center of the device is a tube 20 85 upon which is insulatingly wound a wire 21 forming the resistance clement ot the heater. Around this is a Second tube 22, and the space between these tubes and around the wire is filled with some non-conducting and heat refractory material as powdered magnesium oxid. The ends of the resistance element are provided with terminals 23 and 24 which are carried out thru an opening near the upper end of tube 20, and are covered by a suitable tube 25 which may, in tact, be an extension oi" the cable 14. The ends of the inner tube 20 are then (or previously) expanded and united by brazing or otherwise to the outer tube 22. The parts 20, 21 and 22 form a hollow or tubular heater, the tubular space being repre.- sented by A.

Between the inner wall of the casing 10 and the outer wall of the heater 20-22 is a 105 tube 26 which divides this space into the annular spaces B and C. The tube 26 is somewhat shorter than the heating tube and is held in place by wings 2T on the inner faces of heads 16 and 17. These wings divide 110 these faces into a number of parts as shown in Fig. 3, and the spaces between the wings are concave as shown in Figs. 1 and 2. The heating tube 20,-22 and the partition tubel 26 are held loosely in place by the heads 16 and 17. These tubes are somewhat shorter than the `spacesbetween the heads which conne them, and this allows for variations `of expansion and contraction.

The wires 28 and 29 of the cable 14 may be continuations of the wires 23 and 2%, or the two sets may be Iconnected together in any convenient manner.

The device is filled with some liquid nonconductor for electricity, such as kerosene, to a convenient point between heads 11 and 16, and it is lowered toa position in the well adjacent to the oil bearing sand. When the electric current is turned. on the walls 20 and 22 are heated, and this heat is radiated to the liquid in contact with these walls. The liquid thus heated is that within the tubular space A and that within the annular space B. The heatingof the oil within the space A causes 'an upward flow from the space below the head 17 to the space above head 16, and a consequent reverse flow thru recesses 19 in head 16, the space C and the recesses 19 in head 17 to the space under 17. I TheV heat radiated from wall 22 causes an upward How of oil in space B, over the upper edge of tube 26 and down` th-ru space C, and thence under the lower edge of, tube 26 back vto space B. The arrows on Figs. 1 and 2 show the course of the circulation.

In this operation heat is radiated to the liquid from the vtube 20-22, and is radiated from the liquid thru the tube 10 to the oil Within the well. This causes an upward flow of the liquid adjacent to the heating tube and a downward flow adjacent to the inner wall of the tube 10.` The tube 26 is a partition which divides these two currents from each other. lVithout such partition, the contact between upward and downward flowing currents would cause eddies which would retard the velocity of the circulation. `Title this partition,l the two currents flow smoothly and rapidly and prevent the possibility of one part of the device being heated to a much higher temperature than other parts.

What I claim is:

1. In a device ot' the class described, a shell, a central heating element, a circulating medium within the shell and heated by the heating element, and VV'a partition dividing the upward and downward moving currents of the Circulating inediuni 'from each other.

2. In a device of the class described a cylindrical shell, a central heating element, a circulating medium within the shell and heated by the heating element, and a tube surrounding the heating element and dividing the space between such element and the shell into two parts thru which parts the mediumy circulates.

. 3. In device of the class described a vertical 'disbular shell of great length as compared to its diameter, a cent-ral heating element extending longitudinally thru a considerable length of said shell, a liquid within the shell and subnierging the heating ele ment, and a tubular partition dividing the space between the heatingl element and the shell into two parts, said Adevices being so constructed that the liquidv within the shell flows in one di-rectionl` thru the interior of the partition and in the opposite' direction exterior to such partition.

1. In a device of the class described, a shell, a liquid therein, and a tube immersed in said liquid, said parts being so constructed that the liquid circulates in one direction thru the tube and in the other direction along the exterior surface of the tube.

5. In a device ot' the class described a vertical tubular casing, a tubular heating element therein, a tubular partition between the casing and the heating elementy and a liquid within the casing and submerging the heating element.

6. In a device of the class described a vertical tubular casing, a tubularl heating element within the casing, a liquid in the casing and submerging the heating element, said parts being so constructed that the liquid ilows upward along both 'walls of the heating element and downward along the inner lwall of the'casing, and a tubular partition dividing theupward and downward flowing currents from each other.

7. In a device of the class described a vertical tubular casing, heads closing the ends of the casing. a central heating element within the casing, a tube dividing the space between the heating element and the casing into two annular spaces, supporting heads within the casing and serving to hold the heating element and the tube in proper relationship to the casing, said supporting 'heads having openings therethru, and a circulating liquid within the casing and subinerging the parts therein.A

S. Ina device of the class described, the combination with a` chamber having a liquid therein, of a vertical heating element and a tube surrounding the heating element and spaced therefrom, said heating element and surrounding tube being submerged 'in the liquid of the chamber, said parts being so arranged that the liquid in the chamber circulates upward between the heating element and the tube and downward in the chamber along the exterior vsurface of the tube.

9. In a device of the. class described, the combination with a chamber containing a liquid, of a vertical heating element, heads extending laterally from the ends of the heating element and having wings on their inner faces, and a tube mounted upon said h wings and held removed a short distance from the heads so that the liquid in said chamber may circulate around the ends of the tube and in op osite directions along its inner and outer aces.

10. In a device of the class described, the combination with a chamber containing a 10 liquid, of a vertical heating element, heads extending laterally from the ends of the eatingv element, a tube somewhat shorter than the distance between the heads and surrounding the heating element at a short distance therefrom, and a slipping connection between the heating element and tube to accommodate expansion and contraction of said heating element.

CASPER L. REDFIELD. 

